The present invention relates to an apparatus for adsorption treatment of a gaseous medium, and more particularly to an apparatus for adsorbing moisture from air used for drying synthetic plastic granulate in a supply container of an injection molding machine.
There are already known various apparatuses of the type here under discussion, which generally include an adsorption circuit which connects the supply container to an adsorption chamber filled with at least one regeneratable adsorbent in which the air or other gaseous medium to be used for drying the granulate in the supply container is deprived of moisture, and a regeneration circuit in which an additional adsorption chamber is interposed which is also filled with the regeneratable adsorbent which has been previously saturated with moisture and which is now regenerated by being traversed by hot air. When the firstmentioned adsorption chamber is saturated with moisture, it is included with the regeneration circuit, while the regenerated additional adsorption chamber is included into the adsorption circuit and, being traversed by the gaseous medium to be demoisturized, adsorbs moisture therefrom. The adsorption and regeneration circuits may either include separate blowers or other propelling devices for the gaseous medium to be dried and the regeneration medium, respectively, or a shared propelling device may be provided which propels the media through the respective circuits and the respective adsorption chambers. The transfer of the first-mentioned adsorption chamber into the regeneration circuit and of the additional adsorption chamber into the adsorption chamber, and vice versa upon saturation of the additional adsorption chamber, is accomplished by means of valves interposed into the adsorption and regeneration circuits. Heating devices are included in the circuits, which heat the gaseous medium to be dried to a temperature sufficient for drying the granulate in the supply container, and the regeneration medium to a regeneration temperature. The operation of the apparatus may be controlled in dependence on the temperatures prevailing in the respective circuits, and a sensing means may be provided in the respective circuits to sense the temperatures prevailing therein.
It will be appreciated that the above-discussed apparatus is rather complex and expensive in terms of capital investment and operating costs. More particularly, the valves which are needed for switching the two adsorption chambers between the two circuits are of a complex construction and difficult to manufacture and, consequently, rather expensive. The most important factor contributing to the complexity of the valves and their cost is that these valves must be so constructed as to under all circumstances prevent the humid air from entering the supply container.